Tsumiki is a young girl with brown eyes and brown hair. Her long hair is styled in a ponytail and keeps long bangs on both sides of her face.
While in middle school, Tsumiki wore a school uniform that consisted of a tan colored jacket with a black edge over a white colored button shirt and a red tie, navy skirt, black stockings, and black shoes.
Tsumiki has been shown to wear a light colored turtleneck under a pink cardigan.
Tsumiki is a kind girl who cared deeply for her step-brother Megumi and would often times scold him for getting himself into many fights.
In elementary school, Tsumiki's mother married Toji Fushiguro and Toji's son, Megumi, became her step-brother. Their parents later disappeared without a trace. She studied at Saitama Urami East Junior High along with her brother. Tsumiki would check up on her brother since he would often get into fights. In her third year at Saitama Urami East Junior High, she and two classmates went to Yasohachi Bridge one night where Tsumiki was cursed and fell into a coma, along with other victims across the country. 
During an investigation at Yasohachi Bridge, Megumi discovered that Tsumiki might be connected to the investigation. Megumi contacted Kiyotaka Ijichi to check on his sister, who informed him that Tsumiki's condition remained unchanged.
Pseudo-Geto had already marked Tsumiki prior to the events at Shibuya, casting Idle Transfiguration on her and another person, imbuing the non-sorcerers with cursed energy like Junpei had been. To the former he gave strength as vessels and to the latter he gave the ability to use cursed techniques. After waking Tsumiki from her coma, Psuedo-Geto reveals she and the others must enter into a darwinian battle in order to truly grasp their newly acquired cursed energy.
Abilities and Powers
Currently, nothing is known about her abilities.
- Tsumiki's surname contains the kanji for "bend down, bow" (伏 fushi?) and "black" (黒 guro?), and her first name contains "port, harbor" (津 tsu?), "beautiful" (美 mi?) and "chronicle" (紀 ki?).